The purpose of the work proposed is to elucidate the interactions of T. taenia formis with the inflammatory system of its natural host, the rat. Demonstration of a sequential development of the capacity to interact with portions of the efferent arm of the immune response, as well as other host inflammatory systems, will have direct implications for the interpretation of survival of taeniid metacestodes. This study will, therefore, futher our knowledge of a natural host-parasite relationship. The specific information sought in this proposal includes: (1) changes in selected host inflammatory cells and specific intracellular enzymes which serve to control immediate allergic reactions, (2) effects of parasites on both host control cells of inflammation and cellular secretions, as well as direct inhibition or inactivation by parasitic components of the chemical mediators of immediate hypersensitivity, and (3) effects of parasitic factors on host cell motility. As a result of the proposed investigations, new insights may be developed into the control and treatment of cysticercosis and hydatidosis in particular, and the results may suggest approaches that will have relevance to study of disease mechanisms in infections with other tissue-invasive organisms. The taeniid cyclozoonoses still remain a significant publich health problem in this country and abroad, and improved measures directed toward therapeutic and prophylactic treatment are needed.